Coquina Based Underwater Mitigation Reef and Method of Making Same

ABSTRACT

A method of forming a concrete block embedded with coquina stone comprising the steps of positioning a layer of sand on the bottom surface of a concrete block form, then positioning a layer of coquina stone above the layer of sand positioned on the bottom surface, then pouring concrete over the layer of sand and the layer of coquina stone, thereafter allowing the concrete to harden to form a concrete block which is then removed from the concrete block form.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Application Ser. No. 61/125,803 filed Apr. 29, 2008 entitled “Coquina based underwater mitigation reef and method of making same” that is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

This present invention relates to artificial underwater reefs replicating a habitat for underwater plant and animal wildlife in general, and in particular, to a mat of concrete blocks that are embedded with coquina or similar rock and a method of construction thereof.

BACKGROUND OF THE INVENTION

In the past, there have been attempts made to create underwater reefs to attract marine animals and plant life. For example, ships have been sunk in the ocean to attract fish and marine life. Similarly, other man-made structures have been used often anchored to the ocean bottom to provide a habitat for fish and marine life. In addition, attempts have been made to recreate habitat following damage to underwater reefs caused by hurricanes. Moreover, when real estate development projects are undertaken on the ocean coasts, many areas require mitigation in the form of creating artificial reefs to compensate for the dredging and removal of hardbottom areas. In the past, boulders or other rocks have been used to create what some refer to as a mitigation reef. However, such prior mitigation reefs have been used but found to provide inadequate habitat for aquatic and marine life. Thus, there is a need to provide an artificial mitigation reef that provides suitable habitat for underwater marine and fish populations.

SUMMARY OF THE INVENTION

Now, heretofore, a product referred to as cable concrete has been used in erosion control applications. Cable concrete comprises mats of concrete blocks where the concrete blocks are held together through ropes, including nylon or metal ropes, and placed over areas where erosion may occur, including stream beds, culverts, etc. Cable concrete is used in a variety of applications including Channel and Slope Protection. It has been used in sewage treatment plant applications and low water crossing applications. It has been used for boat ramps, lakeshore protection, tank crossings, and channel protection for storm sewer outlets. Further, cable concrete mats have been used for storm water management ponds, and access road overflows. Other applications include lakeshore protection, bridge abutment protection, bridge and/or pier protection, as well in landfill applications, and to form access roads. The cable concrete mats have also been used in underwater applications to prevent scour.

In addition, it is well known that natural reefs made of coquina rock provide a desirable habitat for underwater marine life and fish life. Coquina rock or stone contain fragments of shell and sand which protrude from the surface. Raw coquina stone from a quarry looks similar to a clump of sand tightly packed with tiny shells and larger shell fragments. Natural coquina reefs are said to exist off the coast of North Carolina and Florida, as well as Barbados. On-shore quarries where coquina stone may be found are known to exist in Florida.

It has been posited that mats of cable concrete where the concrete blocks have been embedded with coquina stone, or other suitable stone such as coral stone may serve as useful artificial mitigation reefs. Testing to determine whether coquina rock embedded in the concrete blocks of cable concrete would serve as suitable artificial mitigation reefs has been undertaken. It is believed that a suitable artificial mitigation reef requires that the coquina rock stay sufficiently embedded in the concrete, with substantial coverage by the coquina rock over the concrete, and that the underwater marine life grow on the coquina-embedded concrete blocks of the mats of cable concrete.

There are a number of potential different ways to construct coquina stone embedded concrete blocks. For example, 32″ by 32″ inch concrete blocks may be poured and coquina stone placed on top of the wet concrete. Of course, many different size and shaped concrete blocks may be used. The coquina stone may be pushed into the concrete with a flat board or possibly vibrated into the concrete. Using this method, the coquina stone did not embed as well as other methods or provide coverage of the concrete as well as other methods. An alternative method of embedding the coquina stone into the concrete blocks was devised. In this alternative method, 32″ by 32″ open top boxes were constructed that had an interior sidewall height of between 8.5″ and 9″. Again, different size and shaped blocks could be used. Prior to the pouring of concrete into the open top boxes, an inch of sand was evenly spread on the bottom surface of the box. Next, a layer of coquina stone was placed on top of the sand. Next, the concrete was poured over the coquina stone and sand and allowed to harden. When the concrete blocks were removed from the open top boxes, the excess or loose sand came free exposing the coquina stone embedded into the concrete. Experimental tests have been undertaken to determine whether mats of cable concrete that include coquina stone embedded concrete blocks will serve as a suitable artificial mitigation reef. Further, an alternate method to make the coquina stone embedded concrete blocks could be done without the use of sand in the bottom, although it is believed that this would not provide as good of a coquina embedded stone compared to when the sand is used in the process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a mat of cable concrete having concrete blocks embedded with coquina stone and interconnected with polyester rope;

FIG. 2 is a photograph of a series of molds for making cable concrete;

FIG. 3 is another photograph of molds for making cable concrete;

FIG. 4 is a perspective photograph of cable concrete without coquina stone embedded therein.

FIG. 5 is a cutaway view of a concrete forming box or mold containing a layer of sand, a layer of coquina stone, and a layer of concrete, prior to its removal from the concrete forming box or mold.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present embodiments are illustrated as exemplary embodiments that disclose a method of embedding coquina stone into concrete blocks that used in mats of cable concrete that are used to create artificial mitigation reefs. FIG. 1 shows a rendering of a cable concrete mat 10 comprising sixteen concrete blocks 12 that are interconnected with nylon rope 14. Each of the concrete blocks 12 is shown embedded with coquina stone 16. This cable concrete mat 10 embedded with exposed coquina stone 16 may be used as an artificial mitigation reef.

In the preferred embodiment, 32″ by 32″ concrete blocks were formed having a height of 8.5″ to 9″. The cable concrete mats of the present invention are not limited to this size block however. Smaller or larger sized blocks including 16″ by 16″ blocks could also be used. To construct the concrete blocks that are embedded with coquina stone, a preferred method of construction has been devised which preferably includes the steps of positioning about one inch of sand spread evenly over the bottom surface of a concrete forming box, next adding a layer of coquina stone on top of the sand, the layer of coquina stone being of one to two inches thick, and finally, pouring concrete over the layers of coquina stone and sand. Once the concrete has sufficiently set, the concrete blocks are removed and sand in the bottom of the concrete forming box is removed, leaving a layer of exposed coquina stone embedded in the concrete blocks.

In forming a mat of cable concrete where the concrete blocks used in the cable concrete mats are embedded with the coquina stone, it is useful to set up series of concrete forming boxes, that are adapted to allow nylon or steel rope, most preferably polyester rope, to extend into the concrete blocks and connect one concrete block to the next to form a mat of concrete blocks, referred to as cable concrete upon hardening of the concrete. FIGS. 2 and 3 show concrete block forms that can be used to make cable concrete. In this manner, a mat of cable concrete having concrete blocks embedded with coquina stone may be created. The mats may be of varying size, for example, a mat of 36 interconnected blocks may be formed using six rows of six blocks each. More or less concrete blocks may be used depending on the application. Further, the concrete blocks may have any suitable geometry including square, rectangular, octagonal, triangular, trapezoidal, etc. The word block is not intended to limit the invention that blocks that are square or to a cube. In use as an artificial underwater reef, the mats of cable concrete may be placed in near shore areas and be used to create a habitat for underwater marine and fish life.

An even more detailed explanation of a preferred method of construction is set forth below herein. There are at least two suitable ways to position the connecting rope in the blocks for use in creating a mat of cable concrete. The first way is to create a mold that resembles an oversized ice cube tray as shown in FIGS. 2 and 3. The mold size is normally 4 ft wide or 8 ft wide and 16 ft long but is not restricted to that length. The length of the mold can vary depending on the application. The first step is to place approximately one inch of clean sand in the bottom of the mold and then embed the desired stone into the sand. Once the stone is placed, a thin mist of form release is sprayed on the sides of the cubes. This release agent allows the hardened concrete to release from the steel mold during the stripping procedure after the concrete has hardened. The cubes in the mold have grooves built into them in which the rope or cable is placed or stung end to end creating loops on the ends of the mats. This again can be seen in FIGS. 2 and 3. Once the rope or cable is in place concrete is gently poured into each cube for creating the blocks. After the concrete is poured and leveled to the top of the mold the blocks are then gently vibrated. This procedure can be done with an external form vibrator or each individual block can be vibrated with a pencil vibrator. After the blocks are vibrated geotextile can be applied to the bottom of the block or the block may be left somewhat smooth. The geotextile can also be installed on the sub base prior to the mats being installed. This decision will be made by the governing engineer at the time of design. Once the concrete has set up (approximately 12 hours) the molds can be stripped. The mold has a spindle on each end of the mold. A lifting bar that is the same length of the mold is hooked to a crane, fork lift ECT and is hooked to the spindles. The mold is lifted up and automatically rolls over. The form is set back down and the cam locks are released on the side of the mold, and the mold is gently picked up a couple of inches off the ground. The sides of the concrete blocks are tapered and normally slide out of the mold. If the blocks hang up in the cubes gently tap the outside of the mold and the blocks will release from the mold. Once all the blocks have released from the mold raise the mold up high enough to clear the top of the blocks that are placed on the ground and the mold will roll back over and the procedure starts all over again. As noted above, you can also just place the desired stone in the bottom of the mold without the sand base as well. This procedure does not produce as nice a product but it may be acceptable to some. FIG. 4 shows a cable concrete mat, although not embedded with coquina stone.

The second procedure entails just a single mold (referred to as a cube although not required to be a cube in the geometric sense, much like ice cubes of varying geometry are referred to as cubes). The sand and stone is placed in the cube in the same manner as the full mold (ice cube tray style in FIGS. 2 and 3). Four plastic or steel tubes are inserted though the mold in both directions. The concrete is poured into the single cube, vibrated and leveled in the same manner as above. Once the concrete has hardened the steel tubes are removed from the side of the mold. In the case of the plastic tubes they can stay in the concrete. The purpose of these tubes is to create holes that run through the base of the block in both directions. The single cube is then rotated over and lifted in the same manner as above. The block will slide out of the mold and is now an individual block with four holes running through the block in both directions. Once several blocks are manufactured they are placed side by side and end to end crating a matrix of blocks to a desired length and width. Cable or rope is then threaded through the holes in the blocks and connected creating a mat of cable concrete blocks similar to the mat that is poured all in one unit.

FIG. 5 is a cutaway view of a concrete block made in accordance with the preferred method. As seen in FIG. 5, concrete forming box 20 has been filled with a layer of sand 22, preferably one inch thick. A layer of coquina stone 24, preferably one to two inches thick has been placed on top of the layer of sand 22. A cable or rope 26 has been placed through the concrete forming box above the layer of sand 22 and the layer of coquina stone 24. A layer of concrete 28 has been poured over the layer of sand 22 and the layer of coquina stone 24, in a layer that also covers the cable or rope 26.

Normally a 4,000 psi concrete is used but different applications, engineers, or specifications may require concrete of varying strengths. The setting time before the blocks can be removed from the mold is approximately 12 hours but this is determined by the location and temperatures that molds are poured in. The time for placement is a minimum of seven days after the concrete blocks are manufactured. A number of mats of cable concrete may be connected together as desired. The cable concrete mats can be connected together with stainless steel clamps, any type of crimping sleeves that are used in saltwater, and stainless steel straps. The standard connecting distance is every 4 feet on centers, around the perimeter of the mats. It should be noted that it may not always be necessary to connect the mats together once installed.

The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention. 

1. A method of forming a concrete block embedded with coquina stone comprising the steps of: positioning a layer of sand on a bottom surface of concrete block form; positioning a layer of coquina stone above the layer of sand positioned on the bottom surface; pouring concrete over the layer of sand and the layer of coquina stone; allowing the concrete to harden to form a concrete block; removing the concrete block from the concrete block form.
 2. The method of claim 1, wherein the layer of sand is approximately one inch deep.
 3. The method of claim 2, wherein the layer of coquina stone is approximately one to two inches deep.
 4. The method of claim 1, further including the step, prior to the step of pouring the concrete, of positioning a rope or cable within the concrete block form that extends from a point within the concrete block form to a point outside the concrete block form.
 5. The method of claim 4, wherein the cable or rope extends through two sidewalls of the concrete block form.
 6. The method of claim 5, wherein the cable or rope is comprised of polyester.
 7. A method of making a mat of cable concrete including a plurality of concrete blocks embedded with coquina stone, comprising the steps of: preparing a plurality of concrete block forms to be poured with concrete; positioning a layer of sand on a bottom surface of the plurality of concrete block forms; positioning a layer of coquina stone above the layer of sand positioned on the bottom surface of the concrete block forms; positioning a rope or cable within the plurality of concrete block forms that extends from a point within the concrete block forms to a point outside the concrete block forms; pouring concrete over the layer of sand and the layer of coquina stone and the rope or cable in the plurality concrete block forms; allowing the concrete to harden to form a plurality of concrete blocks; removing the concrete blocks from the plurality of concrete block forms.
 8. The method of claim 7, wherein the layer of sand is approximately one inch deep.
 9. The method of claim 8, wherein the layer of coquina stone is approximately one to two inches deep.
 10. The method of claim 7, wherein the rope or cable extends from one concrete block form into an adjacent concrete block form.
 11. The method of claim 7, wherein the connecting step is performed by having a cable or rope extend from one concrete block form into an adjacent concrete block form such that when the concrete hardens, the adjacent concrete blocks are connected by the rope or cable.
 12. The method of claim 1, further including the step, prior to the step of pouring the concrete, of positioning a first plastic or metal tube within the concrete block form that extends all the way through the concrete block form.
 13. The method of claim 12, further including the step, subsequent to the step of positioning the first plastic or metal tube, of positioning a second plastic or steel tube within the concrete block form that is perpendicular to the first plastic or steel tube and that extends all the way through the concrete block form.
 14. The method of claim 12, further including the step of threading rope or cable through the first plastic or metal tube.
 15. The method of claim 12, further including the step of threading rope or cable through the first and second plastic or metal tubes.
 16. The method of claim 15, wherein the concrete block is connected to an adjacent concrete block that was made in accordance with the same process as the concrete block.
 17. The method of claim 15, wherein the concrete block is connected to other concrete blocks made in accordance with the same process as the concrete block to form a cable concrete mat.
 18. The method of claim 1, wherein the coquina stone comprises coral stone.
 19. The method of claim 7, wherein the coquina stone comprises coral stone. 